<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        let arr = ['1','20','-5','3'];
        console.log(arr);

        let arr2 = arr.map(a => parseInt(a)) ;
        console.log(arr2);

        let arr3 = [1,2,3,4]

        let arr4 = arr3.map(ele => ele += 10);
        console.log(arr4)


    </script>
</head>
<body>



</body>
</html>